Birth Weight, Academic Achievement, and Life Chances: A Comparison of Siblings from Childhood into Early Adulthood.

We used multilevel covariance structure analysis to study the relationship between birth weight, family context, development, and educational attainment. Using data from the National Longitudinal Survey of Youth Child Sample (CNLSY79), we build on previous research using sibling-comparisons to estimate the causal relationship between birth weight, subsequent academic achievement, and timely high school completion. Because we compare siblings of different ages, we incorporate family characteristics that vary between children as both predictors of growth and change, and also as time-changing covariates. Our findings indicate that birth weight, even after adjusting for fixed-family characteristics and aspects of the home environment that vary between siblings, is associated with lower reading skills at age 5, subsequent growth, and the likelihood of timely high school completion. Notably, however, the relationship between birth weight and timely high school completion is accounted for by children’s early reading skills, indicating the important role of early-learning differences in the attainment process. Additional analyses, however, provide little evidence that the impact of birth weight is exacerbated by social conditions. Overall, the pattern of findings paints a complex picture of disadvantage, beginning in the womb and extending into early-adulthood.